Although they were both married at the time, Alley reveals that she and Patrick Swayze -- her co-star in 1985's "North and South" -- began an intense emotional relationship while filming together (Alley was still with her second husband, Parker Stevenson, whom she divorced in 1997).

The "Cheers" alum admits that sparks flew between her and Swayze almost immediately. Though they tried their best to keep from "going down that road," ultimately their connection proved too strong -- and the duo fell in love.

"Both of us were married," Alley says, clarifying that the pair did not technically "have an affair."

"But again, I think what we did was worse," she explains. "Because I think when you fall in love with someone when you're married, you jeopardize your own marriage and their marriage. It's doubly bad."

During her sit-down with Jacobs, Alley says she is still friends with Patrick's wife, Lisa Niemi, but that she's not sure if Niemi, who asked Alley to speak at Swayze's 2009 funeral, knows about their relationship.

It seems Alley has a history of falling for her co-stars: earlier this week, Alley also told Barbara Walters that John Travolta was "the greatest love of my life," and that she fought the urge to "run off and marry John" while the two worked together on the set of 1989's "Look Who's Talking."